Fishes and shellfishes have been mainly used in the production of fish cakes which may be prepared, for example, adding starch, common salt, seasonings and water optionally together with other components to ground meat of fish or shellfish, kneading the resulting mixture, forming the same into an arbitrary form and then heating the product to thereby solidify the same by taking advantage of the capability of gelation of proteins contained in the said meat.
These fish cakes are among main processed foods obtained from fishes and shellfishes are an important protein source in Japan. Thus the value of fishes and shellfishes as a protein source may be greatly enhanced by employing them not only in the form of processed foods but also as starting materials for various food products.
When fishes or shellfishes are used as starting materials for various foods, however, the proteins contained therein, having a capability of gelation, would cause gelation in a heat treatment step commonly involved in the preparation of foods, thus forming heterogeneous undissolved lumps. This is seriously disadvantageous since the inherent taste of the food is damaged thereby. Thus it is preferable to eliminate or minimize the capability of gelation of fish proteins in the application of fishes and shellfishes merely as a protein source for various foods, though it is necessary in the production of fish cakes.
Proteinous materials showing no capability of gelation were disclosed in, for example, Japanese Patent Laid-Open No. 63140/1984. However these proteinous materials are one obtained from fish meat and are poor in nutrients such as calcium or iron. In addition, a proteinous material produced from fish bodies from which the internals and/or skins are removed, according to the process as disclosed in the above reference has an unpleasant texture and fish oil produced therefrom would be oxidized. Thus these products are unsuitable as foods.
Accordingly it is an object of the present invention to provide a process for producing a highly nutritious proteinous material available in various foods from fish bodies which still contain bones but from which the internals and/or skins have been removed.
It is another object of the present invention to provide a process for producing a proteinous material having a small capability of gelation and containing large amounts of nutrients such as calcium and iron, which is highly available in various foods unlike conventional fish meal which is available only in feeds, from fishes and shellfishes.
Further it is another object of the present invention to provide a process for preparing an unoxidized fish oil and a proteinous material, which is available in various foods unlike conventional fish meal available only in feeds, from fishes and shellfishes rich in fats.